Oligomers in polyethylene furanoate - identification and quantification approach via LC-UV LC-MS response ratio
Polyethylene furanoate polymer is intended to be used as a food contact material. A PEF polymer sample was investigated for its oligomer composition by solvent extraction and using HRLC-MS. The 20 oligomers found were divided into four groups: group I contains cyclic oligomers consisting of furandicarboxylic acid and monoethylene glycol units, group II comprises cyclic oligomers consisting of furandicarboxylic acid, monoethylene glycol units and one diethylene glycol unit, group III are cyclic oligomers were two monoethylene glycol units are substituted by diethylene glycol units and group IV are linear oligomers consisting of furandicarboxylic acid and monoethylene glycol units. Oligomers of group I account for around 87% of the total oligomer content, group II oligomers 12% and group III oligomers 1%. The contribution of group IV oligomers is very small: less than 0.05%. MS-MS experiments showed similar fragmentation patterns for all oligomers. The results of this study demonstrate that oligomers are abundant in the PEF material and are potential migrants to foods that are in contact with the polymer. Oligomers of group I and group II have the same absorption maxima in UV detection which was used to develop a quantification approach for these oligomers using dimethyl 2,5-furandicarboxylate as external standard.